Systems and methods for avoiding neural stimulation habituation

Abstract

An embodiment relates to a method for delivering a vagal stimulation therapy to a vagus nerve, including delivering a neural stimulation signal to non-selectively stimulate both afferent axons and efferent axons in the vagus nerve according to a predetermined schedule for the vagal stimulation therapy, and selecting a value for at least one parameter for the predetermined schedule for the vagal stimulation therapy to control the neural stimulation therapy to avoid physiological habituation to the vagal stimulation therapy. The parameter(s) include at least one parameter selected from the group of parameters consisting of a predetermined therapy duration parameter for a predetermined therapy period, and a predetermined intermittent neural stimulation parameter associated with on/off timing for the intermittent neural stimulation parameter.

1. A method, comprising:
 delivering a heart failure therapy, including stimulating a vagus nerve and avoiding physiological habituation to stimulating the vagus nerve, wherein: 
 stimulating the vagus nerve includes non-selectively stimulating both afferent axons and efferent axons in the vagus nerve using a stimulation signal having a plurality of modifiable stimulation parameters, wherein the modifiable stimulation parameters include at least one modifiable neural stimulation schedule parameter; and 
 avoiding physiological habituation includes stimulating the vagus nerve according to a stimulation schedule independent of heart rate, and limiting modification of the at least one neural stimulation schedule parameter using a programmed limit for allowed modifications to the at least one modifiable neural stimulation schedule parameter. 
 
     
     
       2. The method of  claim 1 , wherein the modifiable stimulation parameters further include modifiable amplitude for the stimulation signal. 
     
     
       3. The method of  claim 1 , wherein the modifiable stimulation parameters further include a modifiable pulse width for the stimulation signal. 
     
     
       4. The method of  claim 1 , wherein the modifiable stimulation parameters further include a modifiable frequency for the stimulation signal. 
     
     
       5. The method of  claim 1 , wherein stimulating the vagus nerve includes delivering intermittent stimulation, the intermittent stimulation including a train of neural stimulation pulses during a portion of a stimulation period and no neural stimulation pulses during another portion of the stimulation period, and the modifiable stimulation parameters include at least one modifiable neural stimulation schedule parameter for the train of neural stimulation pulses. 
     
     
       6. The method of  claim 5 , wherein the at least one modifiable neural stimulation schedule parameter includes a duty cycle of the stimulation period for the train of neural stimulation pulses. 
     
     
       7. The method of  claim 5 , wherein the at least one modifiable neural stimulation schedule parameter includes a duration for the train of neural stimulation pulses. 
     
     
       8. The method of  claim 5 , wherein the train of neural stimulation pulses includes a first train of neural stimulation pulses of a first polarity and a second train of neural stimulation pulses of a second polarity opposite to the first polarity, and the modifiable stimulation parameters includes separate modifiable stimulation parameters for the first and second trains of neural stimulation pulses. 
     
     
       9. The method of  claim 1 , wherein avoiding physiological habituation includes limiting modifications of the duty cycle of the stimulation period using at least one of a programmed maximum allowable duty cycle or a programmed allowable range for allowed modifications to the duty cycle of the stimulation period for the train of neural stimulation pulses. 
     
     
       10. The method of  claim 1 , wherein avoiding physiological habituation includes limiting modifications of the duration for the train of neural stimulation pulses using at least one of a programmed minimum duration or a programmed allowable range for allowed modifications to the duration for the train of neural stimulation pulses. 
     
     
       11. The method of  claim 1 , wherein the modifiable stimulation parameters include a modifiable frequency of approximately 20 Hz, a modifiable pulse width of approximately 300 microseconds, and a modifiable duty cycle between 10% and 20% for a stimulation period of approximately 1 minute. 
     
     
       12. A neural stimulator, comprising:
 a neural stimulation delivery system configured to non-selectively stimulate both afferent axons and efferent axons in a vagus nerve; and 
 a controller operationally connected to the neural stimulation delivery system, the controller configured to deliver a programmed heart failure therapy through the neural stimulation delivery system according to a programmed neural stimulation schedule independent of heart rate, the programmed heart failure therapy including a stimulation signal with modifiable stimulation parameters, the modifiable stimulation parameters including at least one modifiable schedule parameter, the controller including a neural stimulation scheduler with a programmed limit for allowed modifications to the at least one neural stimulation schedule parameter. 
 
     
     
       13. The stimulator of  claim 12 , wherein the controller is configured to deliver the programmed heart failure therapy with the modifiable stimulation parameters, the modifiable stimulation parameters further including at least one of a modifiable duration, a modifiable pulse width, or a modifiable frequency for the stimulation signal. 
     
     
       14. The stimulator of  claim 12 , wherein the controller is configured to deliver the programmed heart failure therapy including an intermittent stimulation signal, the intermittent stimulation signal including a train of neural stimulation pulses during a portion of a stimulation period and no neural stimulation pulses during another portion of the stimulation period, and the at least one modifiable neural stimulation schedule parameter includes at least one of a duty cycle of the stimulation period, a duration, or a start and stop timing for the train of neural stimulation pulses. 
     
     
       15. The stimulator of  claim 12 , wherein the controller includes a neural stimulation scheduler, the neural stimulation scheduler including a programmed limit for limiting modifications of at least one of the duty cycle of the stimulation period using a programmed maximum allowable duty cycle or a programmed allowable range for allowed modifications to the duty cycle of the stimulation period, or the duration for the train of neural stimulation pulses using a programmed minimum duration or a programmed allowable range for allowed modifications to the duration for the train of neural stimulation pulses. 
     
     
       16. A neural stimulator, comprising:
 a neural stimulation delivery system configured to non-selectively stimulate both afferent axons and efferent axons in a vagus nerve; 
 a therapy feedback sensor; and 
 a controller operationally connected to the neural stimulation delivery system and to the therapy feedback sensor, wherein:
 the controller is configured to deliver a programmed heart failure therapy through the neural stimulation delivery system according to a programmed neural stimulation schedule independent of heart rate, the programmed heart failure therapy including a stimulation signal with modifiable stimulation parameters, the modifiable stimulation parameters including at least one modifiable schedule parameter; 
 the controller is configured to receive a therapy feedback signal from the therapy feedback sensor and modify at least one modifiable stimulation parameter in response to the therapy feedback signal; and 
 the controller includes a neural stimulation scheduler with a programmed limit for allowed modifications to the at least one neural stimulation schedule parameter. 
 
 
     
     
       17. The stimulator of  claim 16 , wherein the therapy feedback sensor includes at least one of a blood pressure sensor, a heart rate sensor, or a respiration sensor. 
     
     
       18. The stimulator of  claim 16 , wherein the controller is configured to deliver the programmed heart failure therapy with the modifiable stimulation parameters, the modifiable stimulation parameter further including at least one of a modifiable duration, a modifiable pulse width, or a modifiable frequency for the stimulation signal. 
     
     
       19. The stimulator of  claim 16 , wherein:
 the controller is configured to deliver the programmed heart failure therapy including an intermittent stimulation signal, the intermittent stimulation including a train of neural stimulation pulses during a portion of a stimulation period and no neural stimulation pulses during another portion of the stimulation period; 
 the at least one modifiable neural stimulation schedule parameter includes at least one of a duty cycle of the stimulation period, a duration for the train of neural stimulation pulses, or a start and stop timing for the train of neural stimulation pulses; and 
 the controller is configured to receive the therapy feedback signal from at least one of the blood pressure sensor, the heart rate sensor, or the respiration sensor and to modify at least one of the duty cycle, the duration, or the start and stop timing for the train of neural stimulation pulses in response to the therapy feedback signal. 
 
     
     
       20. The stimulator of  claim 19 , wherein the neural stimulation scheduler includes a programmed limit for limiting modifications of at least one of:
 the duty cycle of the stimulation period using a programmed maximum allowable duty cycle or a programmed allowable range for allowed modifications to the duty cycle of the stimulation period; or 
 the duration for the train of neural stimulation pulses using a programmed minimum duration for the train of neural stimulation pulses or a programmed allowable range for allowed modifications to the duration for the train of neural stimulation pulses.